We evaluated 40 children with spastic hemiplegia due to cerebral palsy for sensory function and relative limb size in the affected and unaffected upper extremities. Sensory function of each limb was evaluated with respect to stereognosis (12 objects), two-point discrimination, and proprioception. Four size measurements of each limb were made: arm and forearm circumference and forearm and forearm-hand length. This study showed that 97% of the spastic limbs had a stereognosis deficit, 90% had a two-point discrimination deficit, and 46% had a proprioception deficit. Thus sensory deficits are the rule rather than the exception in children with spastic hemiplegia. Those children with severe stereognosis deficits had significantly smaller limbs in all four measurement parameters than the children with mild or moderate stereognosis deficits. In the preoperative evaluation of children with spastic hemiplasia, severe size discrepancy is a physical examination tool that can be used as a predictor of severe sensory deficits. This information is helpful for the hand surgeon in establishing realistic surgical goals.